Abstract: The container covers stack together in two different ways. First, the covers can be stacked into an “aligned” stack. The aligned stack provides structural rigidity for bulk handling during manufacturing. Second, the covers can be stacked into a “locked” stack. The locked stack provides even more structural rigidity than does the aligned stack and is useful when storing unused covers. The container cover includes a first closure portion, an engagement portion, and an alignment portion. The base includes a second closure portion. The first closure portion of the cover is sealingly engageable with the second closure portion of the base to define a sealed storage area. The alignment portion of the cover is engageable with the alignment portion of a second cover to form an aligned cover stack. The engagement portion of the cover is engageable with the engagement portion of a second cover to form a locked cover stack.